Samacheer Kalvi 8th Maths Guide Chapter 4 Life Mathematics Ex 4.4

February 23, 2022

Tamilnadu Samacheer Kalvi 8th Maths Solutions Chapter 4 Life Mathematics Ex 4.4

Question 1.
Fill in the blanks
(i) A can finish a job in 3 days whereas B finishes it in 6 days. The time taken to complete the job working together is __________days.
Answer:
2 days

(ii) If 5 persons can do 5 jobs in 5 days, then 50 persons can do 50 jobs in _________ days.
Answer:
5

(iii) A can do a work in 24 days. If A and B together can finish the work in 6 days, then B alone can finish the work in ________ days.
Answer:
8

(iv) A alone can do a piece of work in 35 days. If B is 40% more efficient than A, then B will finish the work in ___________days.
Answer:
25

(v) A alone can do a work in 10 days and B alone in 15 days. They undertook the work for ₹ 200000. The amount that A will get is .
Answer:
₹ 1,20,000

Question 2.
210 men working 12 hours a day can finish ajob in 18 days. How many men are required to finish the job in 20 days working 14 hours a day?
Answer:
Let the required number of men be x.

Hours	Day	Men
12	18	210
14	20	x

More working hours ⇒ less men required.

Question 3.
A cement factory makes 7000 cement bags in 12 days with the help of 36 machines. How many bags can be made in 18 days using 24 machines?
Answer:
Let he required number of cement bags be x.

Days	Machines	Cement bags
12	36	7000
18	24	x

Question 4.
A soap factory produces 9600 soaps in 6 days working 15 hours a day. In how many days will it produce 14400 soaps working 3 more hours a day?
Answer:
Let the required number of days be x.

Soaps	Hours	Days
9600	15	6
14400	(15 + 3) = 18	x

Question 5.
If 6 container lorries can transport 135 tonnes of goods in 5 days, how many more lorries are required to transport 180 tonnes of goods in 4 days?
Answer:
Let the number of lorries required more = x.

Container lorries	Goods (tonnes)	Days
6	135	5
6 + x	180	4

As the goods are more ⇒ More lorries are needed to transport.
∴ It is direct proportion.
∴ Multiplying factor = 180/135
Again if more days ⇒ less number of lorries enough.
∴ It is direct proportion.
∴ Multiplying factor = 5/4
∴ 6 + x = 6×180/135×5/4